Pub Date : 2024-10-30DOI: 10.1016/j.jsames.2024.105213
Maurício Rodrigo Schmitt , Agustín Guillermo Martinelli , Pedro Henrique Morais Fonseca , Cesar Leandro Schultz , Marina Bento Soares
Traversodontid cynodonts form one of the most abundant tetrapod clades in continental Triassic beds of southern Brazil, with more than eleven species described. Within this clade, Protuberum cabralense is one of its most bizarre members, characterized by a robustly built skull and the presence of rounded protuberances in the dorsal surface of the ribs, ilium and neural spines in presacral vertebrae. The holotype and paratypes were collected in the 1970's but described only in 2009, being positioned in the clade Gomphodontosuchinae. Here we reanalyzed the skull of the holotype specimen and reinterpreted some anatomical traits, such as the number of upper incisors, position of the paracanine fossa, number of postcanines, morphology of the pterygo-paraoccipital foramen, among others. Through CT scan images the endocranial cavities are described and compared with Santagnathus mariensis (whose endocranial cavities are firstly described here) and other traversodontids. Also, two new occurrences of the species are presented, increasing its geographical distribution within the Dinodontosaurus Assemblage Zone (Pinheiros-Chiniquá Sequence, latest Ladinian-earliest Carnian) and its relevance to biostratigraphy. The reinterpretation of several traits resulted in a novel phylogenetic placement for Protuberum cabralense, nested outside the Gomphodontosuchinae clade, even as an earlier divergent than massetognathine forms.
{"title":"Craniodental reinterpretations and new specimens of Protuberum cabralense, a bizarre traversodontid cynodont from the earliest Late Triassic of Brazil","authors":"Maurício Rodrigo Schmitt , Agustín Guillermo Martinelli , Pedro Henrique Morais Fonseca , Cesar Leandro Schultz , Marina Bento Soares","doi":"10.1016/j.jsames.2024.105213","DOIUrl":"10.1016/j.jsames.2024.105213","url":null,"abstract":"<div><div>Traversodontid cynodonts form one of the most abundant tetrapod clades in continental Triassic beds of southern Brazil, with more than eleven species described. Within this clade, <em>Protuberum cabralense</em> is one of its most bizarre members, characterized by a robustly built skull and the presence of rounded protuberances in the dorsal surface of the ribs, ilium and neural spines in presacral vertebrae. The holotype and paratypes were collected in the 1970's but described only in 2009, being positioned in the clade Gomphodontosuchinae. Here we reanalyzed the skull of the holotype specimen and reinterpreted some anatomical traits, such as the number of upper incisors, position of the paracanine fossa, number of postcanines, morphology of the pterygo-paraoccipital foramen, among others. Through CT scan images the endocranial cavities are described and compared with <em>Santagnathus mariensis</em> (whose endocranial cavities are firstly described here) and other traversodontids. Also, two new occurrences of the species are presented, increasing its geographical distribution within the <em>Dinodontosaurus</em> Assemblage Zone (Pinheiros-Chiniquá Sequence, latest Ladinian-earliest Carnian) and its relevance to biostratigraphy. The reinterpretation of several traits resulted in a novel phylogenetic placement for <em>Protuberum cabralense</em>, nested outside the Gomphodontosuchinae clade, even as an earlier divergent than massetognathine forms.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105213"},"PeriodicalIF":1.7,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.jsames.2024.105231
Aldo Manzuetti , Washington Jones , Andrés Rinderknecht , Martín Ubilla , Daniel Perea
Sabertooth cats (Felidae, Machairodontinae) are of particular interest for science, and general audience. Because this morphotype is not present in current faunas, several aspects of their biology are still little known in some taxa. The main goal of this contribution is to estimate the body mass (by using regression equations formulated for extant carnivorous mammals), and also the potential prey mass, of the material assigned to the saber-tooth cat cf. Xenosmilus sp. (MNHN Coll. F. OLIVERAS 31561) of the Late Pliocene-Middle Pleistocene from southern Uruguay. The body mass estimations calculated for this felid are within the range of 347–410 kg (average value 378 kg); while the estimated body size of its typical prey was around 1100 kg, the maximum estimated prey size varies from approximately 1800 to 2500 kg. According to these results, several aspects related to the paleoecology of this felid, referred to predator-prey interactions and its potential impact in the community of large carnivores from the beginning of the Quaternary in a regional context in southern South America, are discussed.
{"title":"Body mass of a large-sized Homotheriini (Felidae, Machairodontinae) from the Late Pliocene-Middle Pleistocene in Southern Uruguay: Paleoecological implications","authors":"Aldo Manzuetti , Washington Jones , Andrés Rinderknecht , Martín Ubilla , Daniel Perea","doi":"10.1016/j.jsames.2024.105231","DOIUrl":"10.1016/j.jsames.2024.105231","url":null,"abstract":"<div><div>Sabertooth cats (Felidae, Machairodontinae) are of particular interest for science, and general audience. Because this morphotype is not present in current faunas, several aspects of their biology are still little known in some taxa. The main goal of this contribution is to estimate the body mass (by using regression equations formulated for extant carnivorous mammals), and also the potential prey mass, of the material assigned to the saber-tooth cat cf. <em>Xenosmilus</em> sp. (MNHN Coll. F. OLIVERAS 31561) of the Late Pliocene-Middle Pleistocene from southern Uruguay. The body mass estimations calculated for this felid are within the range of 347–410 kg (average value 378 kg); while the estimated body size of its typical prey was around 1100 kg, the maximum estimated prey size varies from approximately 1800 to 2500 kg. According to these results, several aspects related to the paleoecology of this felid, referred to predator-prey interactions and its potential impact in the community of large carnivores from the beginning of the Quaternary in a regional context in southern South America, are discussed.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105231"},"PeriodicalIF":1.7,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.jsames.2024.105232
A. Núñez-Blasco , M. De los Reyes , F. Cuadrelli , S. Quiñones , A.E. Zurita
Glyptodonts are probably among the most iconic and enigmatic mammals that ever lived during the Cenozoic of America. One of the main clades, Hoplophorinae, developed since the Miocene a structure unique within mammals, the caudal tube, composed of the union of the distal most caudal rings of the caudal armor. In some taxa, especially in the Late Pleistocene species, the caudal tube suffered significant morphological changes. One extreme case is represented by the giant-sized Doedicurini Doedicurus clavicaudatus, in which the caudal tube is transformed into a kind of “clave” (ie., a widening of the distal part, and some large lateral figures where corneal “spine-like” structure were inserted). It has been suggested that this was used in intraspecific combat rather than having a defensive function. Despite this, almost nothing is known about the morphological evolution of this structure along the evolutionary history of Doedicurini. The finding of new remains of Eleutherocercus sp. (a partial caudal tube and dorsal carapace) from the El Polvorín Formation at the Plio/Pleistocene boundary in the surrounding of Olavarría (Buenos Aires province, Argentina), allow us a better understanding of the morphological evolution of this structure between the Late Miocene/Pliocene Eleutherocercus spp. (ca. 7–2.6 Ma) and the Late Pleistocene Doedicurus clavicaudatus. The extreme modification in D. clavicaudatus involves, among others, the disappearance of the most proximal lateral figures, an increase in the diameter of the I Lat figures and disappearance of the II and III Lat figures; and increase in size and lateralisation of the dorso-ventral pairs (especially the 1st pair).
{"title":"New remains of Doedicurini (Cingulata, Glyptodontidae) from the latest Pliocene/earliest Pleistocene of the Pampean Region (Argentina) shed light on the morphological evolution of the caudal tube","authors":"A. Núñez-Blasco , M. De los Reyes , F. Cuadrelli , S. Quiñones , A.E. Zurita","doi":"10.1016/j.jsames.2024.105232","DOIUrl":"10.1016/j.jsames.2024.105232","url":null,"abstract":"<div><div>Glyptodonts are probably among the most iconic and enigmatic mammals that ever lived during the Cenozoic of America. One of the main clades, Hoplophorinae, developed since the Miocene a structure unique within mammals, the caudal tube, composed of the union of the distal most caudal rings of the caudal armor. In some taxa, especially in the Late Pleistocene species, the caudal tube suffered significant morphological changes. One extreme case is represented by the giant-sized Doedicurini <em>Doedicurus clavicaudatus,</em> in which the caudal tube is transformed into a kind of “clave” (ie., a widening of the distal part, and some large lateral figures where corneal “spine-like” structure were inserted). It has been suggested that this was used in intraspecific combat rather than having a defensive function. Despite this, almost nothing is known about the morphological evolution of this structure along the evolutionary history of Doedicurini. The finding of new remains of <em>Eleutherocercus</em> sp. (a partial caudal tube and dorsal carapace) from the El Polvorín Formation at the Plio/Pleistocene boundary in the surrounding of Olavarría (Buenos Aires province, Argentina), allow us a better understanding of the morphological evolution of this structure between the Late Miocene/Pliocene <em>Eleutherocercus</em> spp. (ca. 7–2.6 Ma) and the Late Pleistocene <em>Doedicurus clavicaudatus</em>. The extreme modification in <em>D. clavicaudatus</em> involves, among others, the disappearance of the most proximal lateral figures, an increase in the diameter of the I Lat figures and disappearance of the II and III Lat figures; and increase in size and lateralisation of the dorso-ventral pairs (especially the 1st pair).</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105232"},"PeriodicalIF":1.7,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.jsames.2024.105230
Luana C. Andrade , Fernando H. de S. Barbosa , Hermínio I. Araújo-Júnior , Rudah R.C. Duque , Eduarda Peters , Hugo Bampi , Johnson S.O. Nascimento , Édison V. Oliveira
The natural tank deposits of northeastern Brazil, particularly those with sedimentary filling, are notable for preserving extensive Quaternary megafauna fossil remains. While previous studies have primarily emphasized taxonomic aspects, ichnological evidence has also been documented. This study reports new trace fossils on megafauna remains from the Lagoa da Pedra natural tank (state of Pernambuco, Brazil), shedding light on behavioral interactions between megafauna taxa and other organisms. Four distinct traces, corresponding to three ichnogenera (Cubiculum, Nihilichnus, and Machichnus), were identified on post-cranial bones, three from Eremotherium laurillardi and one from Xenorhinotherium bahiense. Holes and pits (Nihilichnus nihilicus) on the radius of X. bahiense and the rib of E. laurillardi, along with furrows and scratches (Machichnus fatimae and M. bohemicus) on the rib of E. laurillardi, are attributed to scavenging activities, likely by carnivores. Additionally, furrows observed on the rib and vertebra of E. laurillardi are associated with dermestid insect pupation (Cubiculum ornatus and C. cooperi). These pupal chambers of dermestid insects (Cubiculum) suggest that the final stage of the dry carcasses, before the final burial, probably happened under the dry phase during the Late Pleistocene-Early Holocene.
巴西东北部的天然水槽沉积物，尤其是那些沉积填充物，因保存了大量第四纪巨型动物化石而引人注目。虽然以前的研究主要强调分类学方面，但也有人类学方面的证据。本研究报告了 Lagoa da Pedra 天然水池（巴西伯南布哥州）巨型动物遗骸上的新痕迹化石，揭示了巨型动物分类群与其他生物之间的行为互动。在颅骨后的骨头上发现了四种不同的痕迹，分别对应于三个ichnogenera（Cubiculum、Nihilichnus和Machichnus），其中三个来自Eremotherium laurillardi，一个来自Xenorhinotherium bahiense。在 X. bahiense 的桡骨和 E. laurillardi 的肋骨上发现的孔洞和凹坑（Nihilichnus nihilicus），以及在 E. laurillardi 的肋骨上发现的沟槽和划痕（Machichnus fatimae 和 M. bohemicus），都是食腐动物（很可能是食肉动物）的清扫活动造成的。此外，在 E. laurillardi 的肋骨和脊椎骨上观察到的沟壑与皮壳昆虫（Cubiculum ornatus 和 C. cooperi）的化蛹有关。这些皮壳昆虫（Cubiculum）的蛹室表明，干尸在最后埋葬前的最后阶段可能发生在晚更新世-全新世早期的干燥阶段。
{"title":"Exploring trace fossils on megafauna remains from the Quaternary Lagoa da Pedra tank deposit, northeastern Brazil","authors":"Luana C. Andrade , Fernando H. de S. Barbosa , Hermínio I. Araújo-Júnior , Rudah R.C. Duque , Eduarda Peters , Hugo Bampi , Johnson S.O. Nascimento , Édison V. Oliveira","doi":"10.1016/j.jsames.2024.105230","DOIUrl":"10.1016/j.jsames.2024.105230","url":null,"abstract":"<div><div>The natural tank deposits of northeastern Brazil, particularly those with sedimentary filling, are notable for preserving extensive Quaternary megafauna fossil remains. While previous studies have primarily emphasized taxonomic aspects, ichnological evidence has also been documented. This study reports new trace fossils on megafauna remains from the Lagoa da Pedra natural tank (state of Pernambuco, Brazil), shedding light on behavioral interactions between megafauna taxa and other organisms. Four distinct traces, corresponding to three ichnogenera (<em>Cubiculum</em>, <em>Nihilichnus</em>, and <em>Machichnus</em>), were identified on post-cranial bones, three from <em>Eremotherium laurillardi</em> and one from <em>Xenorhinotherium bahiense</em>. Holes and pits (<em>Nihilichnus nihilicus</em>) on the radius of <em>X. bahiense</em> and the rib of <em>E. laurillardi</em>, along with furrows and scratches (<em>Machichnus fatimae and M. bohemicus</em>) on the rib of <em>E. laurillardi</em>, are attributed to scavenging activities, likely by carnivores. Additionally, furrows observed on the rib and vertebra of <em>E. laurillardi</em> are associated with dermestid insect pupation (<em>Cubiculum ornatus</em> and <em>C. cooperi</em>). These pupal chambers of dermestid insects (<em>Cubiculum</em>) suggest that the final stage of the dry carcasses, before the final burial, probably happened under the dry phase during the Late Pleistocene-Early Holocene.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105230"},"PeriodicalIF":1.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.jsames.2024.105211
Reato Agustina , Oscar A. Martínez , Alexander Cottescu , David Serrat
The cold climate events of the Upper Cenozoic greatly modified the landscape of Patagonia, where a large number of relicts and active landforms of glacial, periglacial and paraglacial origin is preserved. To assess the regional paleoclimatic record when numerical ages are unavailable, the spatial distribution of local depositional landform sequences was analyzed in six mountain ranges located on the eastern margin of the North Patagonian Andes. The analysis of satellite images and digital elevation model, fieldwork research and its integration into a Geographical Information System were used to develop a detailed inventory of mountain landforms. A total of 67 glacial valleys, 97 glacial cirques, 94 moraines, 75 rock glaciers, 103 protalus ramparts, and more than 145 km2 and 100 km2 of surface affected by solifluction and mass wasting processes respectively were mapped. From the analysis of the spatial and altitudinal distribution of landforms, we defined temporal and spatial sequences of morpho-climate importance. We recognized four major morpho-climate events associated with local paleoclimate conditions and one stage of a recent paraglacial adjustment. The oldest cold climate event recognized might be correlated with the Last Glacial Maximum. The results show the rise in the average air temperature and an aridity trend for the study area since the Late Pleistocene. During this lapse, glacial environments evolved to periglacial environments, although was recognized their coexistence in some areas in the same mountain range.
{"title":"Glacial and periglacial geomorphology of the eastern flank of the north Patagonian Andes: Quaternary morphoclimatic evolution","authors":"Reato Agustina , Oscar A. Martínez , Alexander Cottescu , David Serrat","doi":"10.1016/j.jsames.2024.105211","DOIUrl":"10.1016/j.jsames.2024.105211","url":null,"abstract":"<div><div>The cold climate events of the Upper Cenozoic greatly modified the landscape of Patagonia, where a large number of relicts and active landforms of glacial, periglacial and paraglacial origin is preserved. To assess the regional paleoclimatic record when numerical ages are unavailable, the spatial distribution of local depositional landform sequences was analyzed in six mountain ranges located on the eastern margin of the North Patagonian Andes. The analysis of satellite images and digital elevation model, fieldwork research and its integration into a Geographical Information System were used to develop a detailed inventory of mountain landforms. A total of 67 glacial valleys, 97 glacial cirques, 94 moraines, 75 rock glaciers, 103 protalus ramparts, and more than 145 km<sup>2</sup> and 100 km<sup>2</sup> of surface affected by solifluction and mass wasting processes respectively were mapped. From the analysis of the spatial and altitudinal distribution of landforms, we defined temporal and spatial sequences of morpho-climate importance. We recognized four major morpho-climate events associated with local paleoclimate conditions and one stage of a recent paraglacial adjustment. The oldest cold climate event recognized might be correlated with the Last Glacial Maximum. The results show the rise in the average air temperature and an aridity trend for the study area since the Late Pleistocene. During this lapse, glacial environments evolved to periglacial environments, although was recognized their coexistence in some areas in the same mountain range.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105211"},"PeriodicalIF":1.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.jsames.2024.105216
Franco D. Bianchi , Juan Cruz Martínez , Hans-Joachim Massonne , Sergio H. Delpino , Jorge A. Dristas
<div><div>A petrological study, combined with field and microstructural evaluation of metapelites, metabasites and a tonalitic to quartz-dioritic rock of Cerro Catedral, North Patagonian Andes of Argentina, reveals the protracted polyphase deformational and metamorphic evolution of the area during the Late Paleozoic to Mesozoic. The 11-component system Si–Ti–Al–Fe–Mn–Mg–Ca–Na–K–O–H was used to model the bulk-rock composition of a mylonitic garnet- and andalusite-bearing micaschist. For this purpose, a P-T pseudosection was calculated using the GeoPs software and contoured with isopleths and mineral isomodes of interest. Refractory zoned garnet typically exhibits a prograde bell-shaped compositional zoning. Its core (gros + andr<sub>0.29</sub>, spes<sub>0.13</sub>, pyr<sub>0.02</sub>, alm<sub>0.55</sub>) to rim (gros + andr<sub>0.22</sub>, spes<sub>0.05</sub>, pyr<sub>0.04</sub>, alm<sub>0.69</sub>) compositions yield a prograde path from initial conditions of ∼9 kbar and 490–500 °C to ∼12 kbar and 510 °C. The remnant compositions (Si: 3.10–3.18 apfu) of K-white mica of the dominant S<sub>2m</sub>-foliation support these physical conditions. The, thus, calculated low geothermal gradient of 11–14°Ckm<sup>−1</sup> suggests that the studied rocks were transported to a maximum depth of ∼45 km in a shallow paleosubduction zone. Microstructures of coalescent quartz ribbons might indicate a peak temperature around 650 °C after peak pressure conditions. These quartz ribbons of S<sub>2m</sub>-mylonitic foliation are slightly wrapped around sigmoidal syn-kinematic plagioclase (Ab<sub>76</sub>-Ab<sub>83</sub>) containing a S<sub>i</sub>-foliation. The outermost garnet rim (gros + andr<sub>0.08</sub>, spes<sub>0.07</sub>, pyr<sub>0.05</sub>, alm<sub>0.80</sub>) also grew syn-kinematically with the S<sub>2m</sub>, and indicates a dominant tectonic exhumation into the middle crust (5.5 kbar ≈ 20 km) with a subsequent cooling to 550 °C. A randomly oriented mineral assemblage of andalusite and biotite indicates a subsequent low-pressure (<3 kbar) thermal overprint between 627 ± 24 °C and 664 ± 50 °C, calculated by Ti-in-biotite geothermometers, near the ductile-deformed tonalite pluton. High Y<sub>2</sub>O<sub>3</sub> (>1.5 wt%) homogeneous monazite yielded a Middle Jurassic age (170 ± 4 Ma). Subsequent cooling produced large muscovite laths (Si: ∼3.0 apfu) in metapelites prior to the generation of upward open folds and a S<sub>3</sub>-crenulation cleavage below 500 °C and late low-grade S-C mylonites. Microstructures in minerals indicate high-to low-temperatures solid-state deformation in the igneous and country rocks during the cooling phase. A final retrogression by chlorite and sericite overprinted the metapelites and the intrusive at < 400 °C. The deciphered ẞ-shaped P-T-d path provides constraints on the geotectonic evolution of this particular sector of the North Patagonian Andes, from a Gondwanan subduction setting, followed by exhumation with in
{"title":"Metamorphic P-T-d evolution path of ductile-sheared rocks of Cerro Catedral, North Patagonian Andes of Argentina: From high-P/T Late Paleozoic progression to low-P/T Jurassic overprint","authors":"Franco D. Bianchi , Juan Cruz Martínez , Hans-Joachim Massonne , Sergio H. Delpino , Jorge A. Dristas","doi":"10.1016/j.jsames.2024.105216","DOIUrl":"10.1016/j.jsames.2024.105216","url":null,"abstract":"<div><div>A petrological study, combined with field and microstructural evaluation of metapelites, metabasites and a tonalitic to quartz-dioritic rock of Cerro Catedral, North Patagonian Andes of Argentina, reveals the protracted polyphase deformational and metamorphic evolution of the area during the Late Paleozoic to Mesozoic. The 11-component system Si–Ti–Al–Fe–Mn–Mg–Ca–Na–K–O–H was used to model the bulk-rock composition of a mylonitic garnet- and andalusite-bearing micaschist. For this purpose, a P-T pseudosection was calculated using the GeoPs software and contoured with isopleths and mineral isomodes of interest. Refractory zoned garnet typically exhibits a prograde bell-shaped compositional zoning. Its core (gros + andr<sub>0.29</sub>, spes<sub>0.13</sub>, pyr<sub>0.02</sub>, alm<sub>0.55</sub>) to rim (gros + andr<sub>0.22</sub>, spes<sub>0.05</sub>, pyr<sub>0.04</sub>, alm<sub>0.69</sub>) compositions yield a prograde path from initial conditions of ∼9 kbar and 490–500 °C to ∼12 kbar and 510 °C. The remnant compositions (Si: 3.10–3.18 apfu) of K-white mica of the dominant S<sub>2m</sub>-foliation support these physical conditions. The, thus, calculated low geothermal gradient of 11–14°Ckm<sup>−1</sup> suggests that the studied rocks were transported to a maximum depth of ∼45 km in a shallow paleosubduction zone. Microstructures of coalescent quartz ribbons might indicate a peak temperature around 650 °C after peak pressure conditions. These quartz ribbons of S<sub>2m</sub>-mylonitic foliation are slightly wrapped around sigmoidal syn-kinematic plagioclase (Ab<sub>76</sub>-Ab<sub>83</sub>) containing a S<sub>i</sub>-foliation. The outermost garnet rim (gros + andr<sub>0.08</sub>, spes<sub>0.07</sub>, pyr<sub>0.05</sub>, alm<sub>0.80</sub>) also grew syn-kinematically with the S<sub>2m</sub>, and indicates a dominant tectonic exhumation into the middle crust (5.5 kbar ≈ 20 km) with a subsequent cooling to 550 °C. A randomly oriented mineral assemblage of andalusite and biotite indicates a subsequent low-pressure (<3 kbar) thermal overprint between 627 ± 24 °C and 664 ± 50 °C, calculated by Ti-in-biotite geothermometers, near the ductile-deformed tonalite pluton. High Y<sub>2</sub>O<sub>3</sub> (>1.5 wt%) homogeneous monazite yielded a Middle Jurassic age (170 ± 4 Ma). Subsequent cooling produced large muscovite laths (Si: ∼3.0 apfu) in metapelites prior to the generation of upward open folds and a S<sub>3</sub>-crenulation cleavage below 500 °C and late low-grade S-C mylonites. Microstructures in minerals indicate high-to low-temperatures solid-state deformation in the igneous and country rocks during the cooling phase. A final retrogression by chlorite and sericite overprinted the metapelites and the intrusive at < 400 °C. The deciphered ẞ-shaped P-T-d path provides constraints on the geotectonic evolution of this particular sector of the North Patagonian Andes, from a Gondwanan subduction setting, followed by exhumation with in","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105216"},"PeriodicalIF":1.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.jsames.2024.105229
Ariane S. da Silveira , Márcio Cardoso Jr. , Paulo S.G. Paim , José E. Faccion , Roberto S.F. D’Ávila , Hector Leanza
A recurring challenge in geological modeling is bridging the gap between different scales. For example, difficulties arise when connecting outcrop data through production to exploration scale models. An object-based stochastic simulation was performed using outcrop data from the Arroyo La Jardinera area in the southern region of the Neuquén Basin, Argentina. This simulation involved four depositional sequences in a vertical succession that includes turbidites and associated deep marine facies. The aims of this study are (a) to determine the best geological model consistent with field and aerial image data; (b) to validate the application of object modeling to determine facies distribution; (c) to evaluate uncertainties from models based on scarce data. The studied interval covers a transgressive (J1) to regressive succession (J21, J22, and J23) of basin plain to slope depositional settings, featuring sandy and gravelly turbidite channels, turbidite lobes and interlobes, lobe fringes, and muddy slope and basin plain. Each depositional sequence model was constructed using specific input parameters for architectural elements, with lithological proportions based on sedimentary logs. The J1 sequence includes basin plain, lobe fringe, and minor lobe deposits; J21 features turbidite lobes, fringes, and subordinate channels; J22 accommodates turbidite channels scoured into muddy slope facies; and J23 encompasses gravelly and sandy turbidite channels carved on muddy slope facies. The geostatistical modeling of outcrop data has allowed building a quantitative sedimentological model useful for understanding subsurface facies heterogeneity in both exploration (vertical) and production (horizontal) scales.
{"title":"3D stochastic simulation of a deep-water turbidite system: An example from the Los Molles Formation, southern region of the Neuquén Basin, Argentina","authors":"Ariane S. da Silveira , Márcio Cardoso Jr. , Paulo S.G. Paim , José E. Faccion , Roberto S.F. D’Ávila , Hector Leanza","doi":"10.1016/j.jsames.2024.105229","DOIUrl":"10.1016/j.jsames.2024.105229","url":null,"abstract":"<div><div>A recurring challenge in geological modeling is bridging the gap between different scales. For example, difficulties arise when connecting outcrop data through production to exploration scale models. An object-based stochastic simulation was performed using outcrop data from the Arroyo La Jardinera area in the southern region of the Neuquén Basin, Argentina. This simulation involved four depositional sequences in a vertical succession that includes turbidites and associated deep marine facies. The aims of this study are (a) to determine the best geological model consistent with field and aerial image data; (b) to validate the application of object modeling to determine facies distribution; (c) to evaluate uncertainties from models based on scarce data. The studied interval covers a transgressive (J1) to regressive succession (J21, J22, and J23) of basin plain to slope depositional settings, featuring sandy and gravelly turbidite channels, turbidite lobes and interlobes, lobe fringes, and muddy slope and basin plain. Each depositional sequence model was constructed using specific input parameters for architectural elements, with lithological proportions based on sedimentary logs. The J1 sequence includes basin plain, lobe fringe, and minor lobe deposits; J21 features turbidite lobes, fringes, and subordinate channels; J22 accommodates turbidite channels scoured into muddy slope facies; and J23 encompasses gravelly and sandy turbidite channels carved on muddy slope facies. The geostatistical modeling of outcrop data has allowed building a quantitative sedimentological model useful for understanding subsurface facies heterogeneity in both exploration (vertical) and production (horizontal) scales.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105229"},"PeriodicalIF":1.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-26DOI: 10.1016/j.jsames.2024.105217
Federico Lince Klinger , Marcelo Gonzalez , Franco Clavel , María Agostina Grigolo , Guido Gianni , Daniel Richarte , Mario Gimenez
The Precordillera fold-thrust belt, situated within the Pampean flat-subduction segment (27°–33°S), is characterised by enigmatic transversal structures which extend and influence deformation patterns, the full extent of which is yet to be fully elucidated. The Northern Pie de Palo Lineament represents a key example, and has been proposed to play a pivotal role in the development and structural control of the Precordillera. In any case, this lineament has not been subjected to a comprehensive study, which has led to ongoing debate regarding its structural control, persistence, and morphology. This study was therefore focused on this structure, employing multiple geophysical methodologies, including aeromagnetic and gravimetric techniques. This approach enabled the first visualization of the full extension and fault zone of the North Pie de Palo Lineament, which crosses the entire Precordillera fold-thrust belt in a transverse direction. Consequently, it can be posited that this structure would have exerted a conditioning influence on the thermo-mechanical state of the Andean lithosphere, enabled the uplift of mafic bodies and thus influenced the Neogene deformation of the Precordillera fold and thrust belt. The confirmation and characterization of this major structure open new perspectives on the interaction of deep-seated transversal structures with fold belts during the evolution of the southern central Andes.
前褶皱-推力带位于帕姆潘平坦-俯冲段（南纬 27°-33°），其特征是神秘的横向结构，这些结构延伸并影响着变形模式，其全部范围尚未完全阐明。北派德帕洛断裂带（Northern Pie de Palo Lineament）就是一个重要的例子，有人认为它在前山地带（Precordillera）的发展和结构控制中发挥了关键作用。无论如何，对这条线的研究还不够全面，因此关于其结构控制、持久性和形态的争论一直没有停止过。因此，本研究采用了多种地球物理方法，包括航空磁学和重力测量技术，重点研究这一结构。这种方法首次实现了北派德帕洛断裂带的全面延伸和断层带的可视化，该断裂带横向穿过整个前山地带褶皱-推力带。因此，可以推测这一构造对安第斯岩石圈的热机械状态产生了调节作用，使岩浆体得以抬升，从而影响了前褶皱-推力带的新近纪变形。这一主要结构的确认和特征描述为研究安第斯山脉中南部演化过程中深层横向结构与褶皱带的相互作用开辟了新的视角。
{"title":"Geophysical evidence for the North Pie de Palo Lineament in the Precordillera","authors":"Federico Lince Klinger , Marcelo Gonzalez , Franco Clavel , María Agostina Grigolo , Guido Gianni , Daniel Richarte , Mario Gimenez","doi":"10.1016/j.jsames.2024.105217","DOIUrl":"10.1016/j.jsames.2024.105217","url":null,"abstract":"<div><div>The Precordillera fold-thrust belt, situated within the Pampean flat-subduction segment (27°–33°S), is characterised by enigmatic transversal structures which extend and influence deformation patterns, the full extent of which is yet to be fully elucidated. The Northern Pie de Palo Lineament represents a key example, and has been proposed to play a pivotal role in the development and structural control of the Precordillera. In any case, this lineament has not been subjected to a comprehensive study, which has led to ongoing debate regarding its structural control, persistence, and morphology. This study was therefore focused on this structure, employing multiple geophysical methodologies, including aeromagnetic and gravimetric techniques. This approach enabled the first visualization of the full extension and fault zone of the North Pie de Palo Lineament, which crosses the entire Precordillera fold-thrust belt in a transverse direction. Consequently, it can be posited that this structure would have exerted a conditioning influence on the thermo-mechanical state of the Andean lithosphere, enabled the uplift of mafic bodies and thus influenced the Neogene deformation of the Precordillera fold and thrust belt. The confirmation and characterization of this major structure open new perspectives on the interaction of deep-seated transversal structures with fold belts during the evolution of the southern central Andes.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105217"},"PeriodicalIF":1.7,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-25DOI: 10.1016/j.jsames.2024.105215
Fernando Lessa Pereira , Alvaro Penteado Crósta , Pietro Demattê Avona , Marcos Alberto Rodrigues Vasconcelos , Ana Maria Goés
Nova Colinas (NC) is a complex-type impact structure located in the northeast region of Brazil. It was formed in the volcano-sedimentary strata of the Parnaíba Basin, in the northern part of Western Gondwana. With an apparent diameter of approximately 6.5–7 km, its rim exhibits a distinctive magnetic signal, likely associated to basic volcanic rocks from the Mosquito Formation. These rocks present shock deformation, bracketing the maximum age of the impact event to 197 Ma. We use the magnetometric and seismic methods to establish the geophysical signature of NC and it is the structural framework in subsurface, as well as for characterizing the occurrence and extent of the volcanics. The magnetometric maps present two distinct magnetic domains in the region of NC: (i) the northern area is characterized by short-wavelength magnetic anomalies related to the basaltic flows of the Mosquito Formation; and (ii) the southern region, where sedimentary rocks from the Sambaiba Formation occur, which lacks significant magnetic anomalies, a typical pattern of siliciclastic sedimentary strata. The magnetic sources at the structure's rim reach an estimated depth of ∼250 m, and the position of the rim itself has been effectively established by the total horizontal derivative of the tilt derivative (THDR_TDR) technique. The regional magnetic anomaly suggests a deeper source at the center of the structure, possibly caused by strata with high magnetic susceptibility uplifted in the modification stage of crater formation. Magnetometric modeling using the magnetization vector inversion (MVI) method allowed detailed mapping of the volcanic rocks that form NC's rim. Additionally, analysis of the seismic data allowed the identification of two well-marked horizons, interpreted as diabase sills, located at depths of 600 m and 1200 m, respectively. Impact-related deformation represented by structures such as fractures, a central uplift, and reflector discontinuities associated with faulting, fracturing, and brecciation, were also unveiled by the seismic data, as well as the establishment of the depth of the crystalline basement at ca. 2200 m.
{"title":"Magnetometric and seismic investigation of the Nova Colinas impact structure, Parnaíba Basin, Brazil","authors":"Fernando Lessa Pereira , Alvaro Penteado Crósta , Pietro Demattê Avona , Marcos Alberto Rodrigues Vasconcelos , Ana Maria Goés","doi":"10.1016/j.jsames.2024.105215","DOIUrl":"10.1016/j.jsames.2024.105215","url":null,"abstract":"<div><div>Nova Colinas (NC) is a complex-type impact structure located in the northeast region of Brazil. It was formed in the volcano-sedimentary strata of the Parnaíba Basin, in the northern part of Western Gondwana. With an apparent diameter of approximately 6.5–7 km, its rim exhibits a distinctive magnetic signal, likely associated to basic volcanic rocks from the Mosquito Formation. These rocks present shock deformation, bracketing the maximum age of the impact event to 197 Ma. We use the magnetometric and seismic methods to establish the geophysical signature of NC and it is the structural framework in subsurface, as well as for characterizing the occurrence and extent of the volcanics. The magnetometric maps present two distinct magnetic domains in the region of NC: (i) the northern area is characterized by short-wavelength magnetic anomalies related to the basaltic flows of the Mosquito Formation; and (ii) the southern region, where sedimentary rocks from the Sambaiba Formation occur, which lacks significant magnetic anomalies, a typical pattern of siliciclastic sedimentary strata. The magnetic sources at the structure's rim reach an estimated depth of ∼250 m, and the position of the rim itself has been effectively established by the total horizontal derivative of the tilt derivative (THDR_TDR) technique. The regional magnetic anomaly suggests a deeper source at the center of the structure, possibly caused by strata with high magnetic susceptibility uplifted in the modification stage of crater formation. Magnetometric modeling using the magnetization vector inversion (MVI) method allowed detailed mapping of the volcanic rocks that form NC's rim. Additionally, analysis of the seismic data allowed the identification of two well-marked horizons, interpreted as diabase sills, located at depths of 600 m and 1200 m, respectively. Impact-related deformation represented by structures such as fractures, a central uplift, and reflector discontinuities associated with faulting, fracturing, and brecciation, were also unveiled by the seismic data, as well as the establishment of the depth of the crystalline basement at ca. 2200 m.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105215"},"PeriodicalIF":1.7,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-25DOI: 10.1016/j.jsames.2024.105218
Emilio A. Rojas Vera, Juan Pablo Lovecchio, Federico Gustavo Enrique Späth, Ofelia Silio, Pedro Kress, Facundo Pagan, Juliana Continanzia, Mirta Suárez, David Giunta, Sebastián Arismendi
Northern Patagonia, to the north of the Somún Cura Massif along the 39°S parallel, is characterized by the development of a series of Jurassic depocenters, initiating in the Andes to the west, across the Neuquén basin and the Pampean sector (Chelforó sub-basin) towards the Atlantic coast near the location of the Pedro Luro −1 well (onshore Colorado basin), and further east over the Argentine shelf, where multiple Jurassic depocenters form the Colorado, Rawson, and Valdés basins.
Using marine and continental gravity data (Free air and Isostatic anomalies respectively), constrained by well and seismic data, an integrated interpretation workflow for the study area was carried out. The southern limit of the Neuquén Basin is controlled by the Huincul High, an E-W directed structure with a positive gravimetric anomaly, interpreted as a basement high limited by relative gravimetric lows to the north and south of the structure. The eastern sector includes a series of isolated depocenters, separated by basement highs (obliquely oriented) and limited to the south by the E-W anomaly of the Huincul High. These depocenters correspond to the Chelforó sub-basin, which was drilled in a recent exploration campaign obtaining Jurassic ages where seismic interpretation pointed out presumably Jurassic deposits. Between Valcheta and Sierra Grande, this positive anomaly turns NW and becomes the southern boundary of the Pedro Luro depocenter, partially drilled by the Pedro Luro- 1 well, with possibly Tithonian palynological records at total depth. Between the Pedro Luro depocenter and the Chelforó sub-basin some features consistent with basement highs with circular morphology have been identified on gravimetric data, located in the area limited between the Colorado and Río Negro rivers. Jurassic rift depocenters have also been interpreted further east, in the Colorado basin where depocenters are controlled by an E-W oriented basement high, and further east by NW trending structures near the position of the SDRs (seaward dipping reflectors on the continental-oceanic crust transition zone).
The common evolution of these Jurassic depocenters is still poorly understood. They extend for more than 1500 km from the Andes to the Atlantic continental shelf and are controlled by structures located to the north of the Somún Cura Massif. The interpretation of seismic lines, and gravimetric data in areas without deep wells allow the identification of new exploration targets increasing the exploration potential of these basins.
{"title":"Jurassic depocenters development, between colorado basin, chelforó sub-basin and neuquén basin","authors":"Emilio A. Rojas Vera, Juan Pablo Lovecchio, Federico Gustavo Enrique Späth, Ofelia Silio, Pedro Kress, Facundo Pagan, Juliana Continanzia, Mirta Suárez, David Giunta, Sebastián Arismendi","doi":"10.1016/j.jsames.2024.105218","DOIUrl":"10.1016/j.jsames.2024.105218","url":null,"abstract":"<div><div>Northern Patagonia, to the north of the Somún Cura Massif along the 39°S parallel, is characterized by the development of a series of Jurassic depocenters, initiating in the Andes to the west, across the Neuquén basin and the Pampean sector (Chelforó sub-basin) towards the Atlantic coast near the location of the Pedro Luro −1 well (onshore Colorado basin), and further east over the Argentine shelf, where multiple Jurassic depocenters form the Colorado, Rawson, and Valdés basins.</div><div>Using marine and continental gravity data (Free air and Isostatic anomalies respectively), constrained by well and seismic data, an integrated interpretation workflow for the study area was carried out. The southern limit of the Neuquén Basin is controlled by the Huincul High, an E-W directed structure with a positive gravimetric anomaly, interpreted as a basement high limited by relative gravimetric lows to the north and south of the structure. The eastern sector includes a series of isolated depocenters, separated by basement highs (obliquely oriented) and limited to the south by the E-W anomaly of the Huincul High. These depocenters correspond to the Chelforó sub-basin, which was drilled in a recent exploration campaign obtaining Jurassic ages where seismic interpretation pointed out presumably Jurassic deposits. Between Valcheta and Sierra Grande, this positive anomaly turns NW and becomes the southern boundary of the Pedro Luro depocenter, partially drilled by the Pedro Luro- 1 well, with possibly Tithonian palynological records at total depth. Between the Pedro Luro depocenter and the Chelforó sub-basin some features consistent with basement highs with circular morphology have been identified on gravimetric data, located in the area limited between the Colorado and Río Negro rivers. Jurassic rift depocenters have also been interpreted further east, in the Colorado basin where depocenters are controlled by an E-W oriented basement high, and further east by NW trending structures near the position of the SDRs (seaward dipping reflectors on the continental-oceanic crust transition zone).</div><div>The common evolution of these Jurassic depocenters is still poorly understood. They extend for more than 1500 km from the Andes to the Atlantic continental shelf and are controlled by structures located to the north of the Somún Cura Massif. The interpretation of seismic lines, and gravimetric data in areas without deep wells allow the identification of new exploration targets increasing the exploration potential of these basins.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105218"},"PeriodicalIF":1.7,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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